Bruce Dunn's table of rocket-fuel densities at yarchive (was Resources are)

Yes, there's more about this and more on his website:

http://www.dunnspace.com/alternate_ssto_propellants.htm

On 26 March 2012 18:16, hitssquad wrote:

> --- In spacesettlers@yahoogroups.com, Ian Woollard wrote:
> > On 22 March 2012 00:46, Al Globus wrote:
> > > H2/O2 is the bets rocket fuel.
> > Actually, no. The optimum for launch is a tripropellant system where the
> mixture varies over the launch.
>
> The reason is that hydrogen has poor density, so the tankage, pumps and
> pipe mass is very high for any given thrust level; so you are better off
> running with dense fuel early on
>
> Yes. More on fuel densities, from yarchive:
> http://yarchive.net/space/rocket/fuels/fuel_table.html
>
> Notice the difference between hydrogen at 20 degrees Kelvin vs. propane at
> 100 degrees Kelvin. The hydrogen, even though it has to be kept at a much
> lower temperature, has a density of only 70 kg/m^3, whereas the Propane,
> which can be brought down to 100 degrees Kelvin simply by putting it in
> contact with a liquid oxygen tank, has a density of 782 kg/m^3 -- more than
> 11x the density of liquid hydrogen.
>
> From: Bruce Dunn
> Newsgroups: sci.space.policy
> Subject: Re: Kerosene vs Hydrogen fuelled SSTO rockets
> Date: Sun, 09 Feb 1997 09:10:58 -0800
>
> With respect to the subject of this thread, the choice of fuels for an
> SSTO isn't just between kerosene and hydrogen. A number of other fuels are
> quite reasonable alternatives. I reproduce below a cleaned-up version of a
> post I recently made in sci.space.tech on the subject:
>
> A number of alternate fuels have been proposed for use with liquid oxygen.
> Here are some characteristics of these propellant combinations, in
> comparison with the standard fuels hydrogen and RP-1 (Rocket Propellant 1 > kerosene). I have only included fuels with an Isp greater than that of
> RP-1, and have ignored exotics like boranes. See the table notes at the
> end of the article for details of how the calculations were done.
>
> Tank Fuel Bulk Vac.
> Temp Formula MR Dens. Dens. Tc Isp
> K O/F kg/m^3 kg/m^3 K 100:1
>
> NON-HYDROCARBONS
> hydrogen, NBP 20 H2 6.0 70 358 3610 455.9
> UDMH, RT 298 C2H8N2 1.6 786 972 3710 365.4
>
> ALKANES
> methane, NBP 112 CH4 3.0 423 801 3589 368.3
> ethane, NBP 184 C2H6 2.7 544 880 3671 364.6
> propane, NBP 231 C3H8 2.7 582 905 3734 361.9
> propane, 100K 100 C3H8 2.7 782 1014 3734 361.9
> butane, NBP 273 C4H10 2.6 573 894 3734 360.9
> RP-1, RT 298 C12H24 2.5 820 1026 3803 354.6
>
> UNSATURATED HYDROCARBONS
> ethylene, NBP 169 C2H4 2.3 569 874 3888 366.9
> propylene, NBP 225 C3H6 2.3 611 903 3842 364
> 1,2-butadiene, NBP 284 C4H6 2.1 645 914 3982 363.5
> 1,3-butadiene, NBP 269 C4H6 2.1 614 893 3917 359.4
> methylacetylene, NBP 250 C3H4 1.9 671 919 4034 366.9
>
> Hydrogen has an excellent Isp but a rotten bulk density. RP-1 gives an
> excellent bulk density, but a much lower Isp. There are a number of
> alternate propellants shown in the table which fall somewhere between the
> two, having a slightly higher Isp than RP-1 but a lower bulk density.
>
> UDMH (unsymmetrical dimethyl hydrazine) is normally used mixed with
> straight hydrazine (N2H4) and is normally burned with N2O4 as an oxidizer.
> It burns perfectly well however with liquid oxygen, and is a superior fuel
> provided one can tolerate its toxicity and cost.
>
> The light alkanes are all readily available in industrial quantities, are
> good coolants. Going from RP-1 to methane gains 3.8 % in Isp, but costs
> about 22% in density. Other alkanes lie between the performance of methane
> and RP-1.
>
> Propane at room temperature is a non-starter for pump fed engines, as its
> vapor pressure is too high for light weight tanks. Propane is unusual in
> that it will not freeze solid if put in tanks in thermal contact with LOX
> tanks; it has been proposed therefore to use sub-cooled propane.
> Calculations done here show both propane at its normal boiling point, and
> at 100 K, about 10 K above LOX temperature. Sub-cooled propane (at LOX
> temperatures or slightly above to account for imperfect chilling of propane
> by adjacent LOX tanks) is a winner, with a bulk density nearly the same as
> that of RP-1, and a superior Isp.
>
> The light unsaturated compounds are also readily available in industrial
> quantities. These compounds may possibly give polymerization problems when
> used for engine cooling, but again, they may not (particular those which
> are very cold to start with may not warm up enough to cause problems). They
> don't seem to be superior enough to alkanes to make their use worth while,
> particularly considering that they generally have higher chamber
> temperatures than for alkanes with the same Isp.
>
> Table Notes:
>
> Isp calculations were performed on a partial equilibrium basis, assuming
> that recombination reactions stop at the nozzle throat (an approximation of
> real world behavior). Isp values are theoretical values for 100:1 expansion
> into vacuum, and assume a chamber pressure of 20 MPa (approximately 2900
> psi). These conditions are representative of a high pressure, high
> expansion ratio engine that might be used for an SSTO.
>
> Fuel storage temperature is generally at Normal Boiling Point (NBP) which
> is the temperature at which a fuel will equilibrate at if tanks are vented
> to the atmosphere during filling. Exceptions are RP-1 and UDMH at Room
> Temperature (298 K), and one calculation in which propane is chilled to 100
> K, about 10 K above its freezing temperature.
>
> Mixture ratios (MR) are expressed as the mass of oxidizer divided by the
> mass of the fuel (O/F). The MRs given are the optimum for maximal Isp,
> except for H2 which is calculated at a mixture ratio of 6:1, rather than
> the more optimal 4.4 which would give a higher Isp, but a much poorer bulk
> density.
>
> Fuel densities are the density in the fuel tanks. Bulk density is the
> overall density of the propellant combination, with the stated mixture
> ratio and oxygen at a density of 1140 kg/m^3.
>
> Tc is the chamber temperature - it is higher for unsaturated hydrocarbons
> than for alkanes, as the former have energy locked up in the structure of
> their molecules which adds to the energy available from oxidation.
>
> RP-1 is shown with a molecular formula of C12H24 ; this is an
> approximation to something like the average molecular formula (RP-1 has an
> H to C ratio of approximately 2, and an average molecular weight somewhere
> near that of hexadecane, C12H26)
>
> --
> Dr. Bruce Dunn
> General Astronautics Canada, Vancouver B.C.
> http://www.genastro.com/ | 800-577-1117 | 604-876-7640
> Reliable, low-cost transportation to low Earth orbit and beyond
>

--
-Ian Woollard